1. Field of the Invention
The present invention relates to a medical coil, a method of manufacturing the same, and a medical instrument.
2. Background Art
When a calculus forms in an organ such as a biliary tract or a bladder, the calculus has an adverse influence on a patient. Particularly, an enlarged calculus inflicts tremendously large pain on a patient. Thus, treatment is conducted in such a way that a treatment tool (a medical instrument) for an endoscope, which is designed to crush the calculus, is introduced into a body cavity of the patient through a channel for the treatment tool of the endoscope, and captures, crushes, and discharges the calculus from the body or captures and removes the calculus from the body in the captured state.
As such a treatment tool for the endoscope, a treatment tool disclosed in Japanese Unexamined Patent Application, First Publication No. 2006-314714 is known. In the treatment tool, a basket made of a metal element wire is installed on a distal end of a manipulation wire inserted through a sheath having flexibility. The treatment tool is configured to house the basket in the sheath along with the manipulation wire. An operator crushes the calculus using the treatment tool as follows. The operator manipulates a manipulation part connected to a proximal end of the sheath, and moves the manipulation wire forward or backward, thereby capturing the calculus in the basket. The operator pulls the manipulation wire toward the manipulation part, and thereby the basket is strained. As a result, the calculus is pressed and crushed.
In the above-mentioned treatment tool for the endoscope, both flexibility for facilitating the insertion into the body cavity and compressive resistance (resistance to axial compression) for reliably transmitting a force of traction of the manipulation wire for crushing the calculus to the basket of the tip of the manipulation wire are required for the insertion part inserted into the body cavity. Typically, a coil sheath in which the metal element wire is closely wound is frequently used as a configuration having the above-mentioned two characteristics in a relatively balanced way.